This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Rahimi and coworkers published recently, that F-box-containing beta-Trcp1 ubiquitin E3 ligase is involved in angiogenesis by recruiting the phosphorylated sites of VEGFR-2 (vascular endothelial growth factor receptor growth factor receptor 2) [R. D. Meyer, S. Srinivasan, A. J. Singh, J. E. Mahoney, K. R. Gharahassanlou, and N. Rahimi, PEST Motif Serine and Tyrosine Phosphorylation Controls Vascular Endothelial Growth Factor Receptor 2 Stability and Downregulation, Molecular and cellular Biology, 2011, 31, 10: 2010[unreadable]2025.] This project investigates whether phosphorylation on beta-Trcp1 could play a role in the recruitment of VEGFR-2 with beta-Trcp1. Toward this end, the Resource has used mass spectrometry, following a bottom-up approach, to analyze the beta-Trcp1 protein extracted from the cell. We performed digestion on the immune-precipitated samples, before analyzing the samples by nano-LC-MS/MS on the LTQ-Orbitrap (Thermo-Fisher). Preliminary tandem mass spectrometry data did not provide evidence for any phosphorylation sites.